Multivariate Pattern Analysis of fMRI Reveals Striato-Cortical Network Changes in Myoclonus-Dystonia

Currently, the pathophysiology of myoclonus-dystonia (M-D) remains insufficiently understood. This study addresses this gap by adding innovative multivariate pattern analysis (MVPA) to traditional univariate analysis of functional magnetic resonance imaging (fMRI) data.

Data from 18 M-D patients and 18 age-matched healthy volunteers who performed a finger tapping fMRI task were analyzed. Whole-brain univariate and searchlight (MVPA) analysis with varying hemodynamic response function (HRF) delays were employed to examine brain responses associated with the visually guided motor task.

Distinguishing response patterns between M-D patients and healthy volunteers revealed significant response reductions in the putamen, insula, and visual cortex. Compared to univariate analysis, searchlight analysis was more sensitive for brain activity patterns associated with finger tapping in both M-D patients and healthy volunteers. At short HRF delays, increased (pre)motor cortical responses were evident in M-D patients, whereas such responses emerged at a later HRF delay in healthy volunteers.

The task-related effects observed in M-D patients support the involvement of the basal ganglia-thalamo-cortical network. Notably, cerebellar involvement was not strongly implicated in our study. We postulate that inherent deficits in the putamen trigger either premature or downstream compensatory (motor) cortical effects. The potential involvement of the visual cortex in the M-D pathophysiology is new, but its role has been suggested by a previous study investigating visual sensory processing in SGCE gene-positive M-D patients. Our findings, including the innovative searchlight method, pave the way for further studies investigating the complex interplay between brain regions and networks and their role in M-D pathogenesis.